33 lines
1 KiB
GLSL
33 lines
1 KiB
GLSL
shader_type canvas_item;
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render_mode blend_disabled;
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uniform sampler2D u_brush_texture;
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uniform float u_factor = 1.0;
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uniform vec4 u_texture_rect;
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// TODO Could actually level to whatever height the brush was at the beginning of the stroke?
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void fragment() {
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float brush_value = texture(u_brush_texture, SCREEN_UV).r;
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// The heightmap does not have mipmaps,
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// so we need to use an approximation of average.
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// This is not a very good one though...
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float dst_h = 0.0;
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vec2 uv_min = vec2(u_texture_rect.xy);
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vec2 uv_max = vec2(u_texture_rect.xy + u_texture_rect.zw);
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for (int i = 0; i < 5; ++i) {
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for (int j = 0; j < 5; ++j) {
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float x = mix(uv_min.x, uv_max.x, float(i) / 4.0);
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float y = mix(uv_min.y, uv_max.y, float(j) / 4.0);
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float h = texture(TEXTURE, vec2(x, y)).r;
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dst_h += h;
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}
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}
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dst_h /= (5.0 * 5.0);
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// TODO I have no idea if this will check out
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float src_h = texture(TEXTURE, UV).r;
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float h = mix(src_h, dst_h, u_factor * brush_value);
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COLOR = vec4(h, 0.0, 0.0, 1.0);
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}
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